Exploration of P-type Ca2+ channels as drug targets for the treatment of epilepsy or ischemic stroke.
Lingenhöhl K., Small DL., Monette R., Buchan AM., Morley P., Allegrini PR., Fröst LW., Sauer D., Schmutz M., Knöpfel T.
We investigated the neuroprotective efficacy of the P-type Ca2+ channel antagonist daurisoline against electroshock-induced convulsions in rats and mice, hypoxic/hypoglycemic-induced damage in rat hippocampal slices and brain damage induced by occlusion of the middle cerebral artery (MCA) in rats. Daurisoline applied intravenously (i.v.) (bolus of 1-60 mg/kg) reduced the spontaneous activity of rat cerebellar Purkinje cells in a dose-dependent manner, a result demonstrating activity in the brain with systemic administration of the compound. While this effect reversed rapidly in about 10-20 min following bolus-application of the drug at doses of up to 30 mg/kg, a dose of 60 mg/kg consistently induced a depression of respiration followed by death of the animals. Daurisoline administered at 10-30 mg/kg did not prevent electroshock-induced convulsions in mice or rats, nor did it reduce the neuronal damage in hippocampal slices induced by a hypoxic/hypoglycemic insult in vitro by MCA occlusion in vivo. These observations do not support the hypothesis that P-type Ca2+ channels are promising drug targets for the acute treatment of epileptic convulsions and/or ischemic stroke.